Mesh blocks are the smallest geographical area that the Australian Bureau of Statistics defines. Mesh blocks contain on average between 30 and 60 dwellings. In urban areas, the Australian Bureau of Statistics targets a mesh block size closer to 30 dwellings. In rural areas, the number of dwellings in a mesh block may be lower if the properties are distributed over a large area. The 2016 census recognized over 350,000 mesh blocks in Australia.

The Australian Bureau of Statistics uses multiple criteria to define mesh blocks. For example, mesh block boundaries should be consistent and continuous with each other, and mesh blocks should not cross property boundaries. Additionally, mesh blocks should be homogeneous in land use. The types of land use that the Australian Bureau of Statistics defines for mesh blocks include residential, commercial, industrial, parkland, education, and hospital or medical use.